...Zhuming Yang; Gerald Giester The crystal structures of coquimbite and paracoquimbite from the Hongshan Cu–Au deposit, NW China, were refined by single-crystal X-ray diffraction, including the positions of all non-H atoms and hydrogen atoms. The unit-cell parameters of coquimbite are a = 10.9644(15...

...Sonia Ackermann; Biljana Lazic; Thomas Armbruster; Stephen Doyle; Klaus-Dieter Grevel; Juraj Majzlan Abstract Enthalpies of formation of kornelite [Fe 2 (SO 4 ) 3 ·~7.75H 2 O] and paracoquimbite [Fe 2 (SO 4 ) 3 ·9H 2 O] were measured by acid (5 N HCl) solution calorimetry at T = 298.15 K...

...Paul D. Robinson; J. H. Fang Abstract The crystal structure of paracoquimbite—Fe 2 (S0 4 ) 3 ·9H 2 O, space group R 3 , a = 10.93 Å, c = 51.30 Å, Z = 12— has been determined by analogy to the structure of coquimbite, and found to differ only in its stacking sequence. Thus the two minerals...

...F igure 10. XRD data showing kornelite transformation to paracoquimbite at 62% RH. Five lines indicate 0, 7, 23, 43, and 79 days preservation of kornelite powders at 62% RH from bottom to top. Percentages are the weight proportions of each phase estimated from Rietveld refinement. K = Kornelite...

...Figure 6. RH– T phase diagram for Fe 2 (SO 4 ) 3 reproduced from Ackermann et al. (2009) with added observations in this study. The rectangle at 80 °C extending from 20 to 80% RH is the observed transition from paracoquimbite to Fe 2 (SO 4 ) 3 ·5H 2 O. The rectangle from 0 to 10% RH...

... the occurrence of Al. Coquimbite has a homeotypic relationship with paracoquimbite, Fe 4 (SO 4 ) 6 (H 2 O) 12 ⋅6H 2 O; both mineral species belong to the coquimbite group. On the contrary, aluminocoquimbite, Al 2 Fe 2 (SO 4 ) 6 (H 2 O) 12 ⋅6H 2 O, has a different topology and does not belong to that group...

... multi-valent and light elements (Fe 2+ , Fe 3+ , OH − , and H 2 O) that may be challenging to quantify. We synthesized or obtained HHIS—szomolnokite, melanterite, rhomboclase, schwertmannite, ferricopiapite, paracoquimbite, and jarosite—as well as Fe-oxides. These nominally pure samples were...

...Figure 9. Sulfur (S) K -edge k 3 -weighted χ functions ( a ), Fourier transformed (FTs)χ functions ( b ), and real part of Fourier transformed EXAFS spectra ( c ) of reference compounds (Na 2 SO 4 and paracoquimbite) and SO 4 -scorodite (1 M Na + and pH 1.2). (Color online.) ...

...P. B. Moore; T. Araki Abstract Product K, (NH 4 )H 8 Fe 3 3+ (PO 4 ) 6 ·6H 2 O, is based on corner-linking octahedra and tetrahedra and is structurally related to coquimbite, paracoquimbite, and the synthetic Fe 2 (SO 4 ) 3 dimorphs. It is trigonal, а 1 = 9.151(2), с = 16.862(4)A, Z = 2, space...